*clings to* I think you're doing amazing with Chad! I think he's just right -- the right mix of mellow, protective, clever... And I'm almost positive his activity is good.
But some ideas to dwell on, I guess... *ponders* You're getting him involved in music things, you've had him playing the guitar and attending music class, and that's good. He likes Don Kanonji and Hawaiian shirts so we know he likes over-the-top stuff and he might stand to be drawn in by a few of the more outrageous but harmless types in the prison.
Chad's troubled childhood might lead him to get involved with what appear to be troubled children, like Aftran (for like ten seconds until she disillusions him) or Ushiro -- with his own violent tendencies, he might want to help coach them into finding a better way/emotional place?
Zim is also a good candidate on all fronts, orz Zim. You'll just be able to watch him like a TV show, man.
ANYWAY those... are... my thoughts? I hope they're a little helpful in helping you find footing with him. Either way, you have my love for playing him and I think you're amazing with him.